Figure 1.
Tumor response to voluntary aerobic exercise. BALB/c mice bearing 4T1 mammary tumors were randomly assigned to exercise or sedentary controls (n = 11–12/group) starting on day 0. Data are presented as means; error bars represent 95% confidence intervals (CIs). A) Tumor growth rate is statistically significantly slowed by exercise. * P = .004, ANCOVA. B) Representative color composites of immunostaining for apoptosis (cleaved caspase-3, green) in mice that exercised vs sedentary controls. Cellular nuclei are stained with Hoechst 33342 (blue). 5x objective, magnification 100%. Scale bar equals 33 µm. The density of apoptotic cells (cleaved caspase-3+ cells/mm2) is statistically significantly higher in the exercise group compared with sedentary controls. Gray lines = mean; black lines = 95% CI, P = .048, two-sided t test. C) Expression of apoptosis-related proteins in response to exercise. Protein was extracted from 4T1-luc tumors, and expression levels of components of the extrinsic (Fas, Caspase 8) and intrinsic (Bcl-2) pathways, as well as downstream mediators of apoptosis (XIAP, PARP), were visualized on western blots. Band intensity was quantified in comparison with actin loading controls. Both Fas (P < .001) and Caspase 8 (P = .044) expression were statistically significantly increased in mice that exercised, rank sum test. All statistical tests were two-sided.